1. Field of the Invention
The present invention relates to an arrangement for producing metal nanoparticles, and more particularly, to a reactor for producing metal nanoparticles, such as fuel cell catalysts, using a process of γ-ray irradiation.
2. Description of the Related Art
A chemical method is generally used to produce metal nanoparticles such as fuel-cell catalysts. In the chemical method, a metal precursor of reaction materials is reduced and thus the metal nanoparticles are generated. The reaction materials include a metal salt used as the metal precursor, a solvent, a dispersing agent (stabilizer), a reducing agent, and the like. In addition, energy irradiation methods for irradiating electron beams, microwaves, ultraviolet rays to reaction materials may be used.
In recent years, as one of the energy irradiation methods, a method of irradiating γ-rays that are high energy electromagnetic waves to the reaction materials has been used to produce the metal nanoparticles.
According to this γ-ray irradiation method, the γ-rays are irradiated to the reaction materials, except for the reducing agent, to generate hydrated electrons, and materials of a variety of chemical species and metal nanoparticles, such as fuel-cell catalysts, are produced by allowing the hydrated electrons to act as a reducing agent for reducing the metal precursor. In order to produce the metal nanoparticles using the γ-ray irradiation method, there is a need for a reactor that can uniformly mix the reaction materials and irradiate the γ-rays with a uniform intensity to the reaction materials.
A contemporary reactor used for performing the γ-ray irradiation includes a container for receiving the reaction materials and an agitator for agitating the reaction materials. The agitator is designed to be operated by a driving device such as magnetic, electric, and/or electronic circuit devices.
The driving device, however, may be damaged by the high energy γ-rays. This kind of damage may cause the malfunctioning or even a breakdown of the agitator, and thus the reaction materials may not be uniformly mixed.
Furthermore, since the container of the contemporary reactor is formed in a cylindrical shape, the γ-rays cannot be uniformly irradiated into the reaction materials due to γ-rays inherent property that γ-rays are irradiated in all directions from the γ-ray irradiator and the intensity of the γ-ray is inversely proportional to the square of a distance.
The above information disclosed in this Background discussion of related art is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.